GEOTECHNICAL SERVICES

Geotechnical Design

A F Howland Associates provide extensive geotechnical services and have extensive experience with the development of buildings and structures, from single houses to multi-storey offices and commercial/industrial structures.

Based on the findings of the site investigation and the requirements of the client details, recommendations and design options can be provided upon the following:  

• Existing foundations (dimensions and composition)
• Bearing capacity estimation
• Settlement analysis
• Design loadings for piled foundations
• Recommendations for conventional rafts or piled rafts

Subsidence Investigations and Analysis

Subsidence is a major cause of failure of structures due to excessive settlement of foundations.  There can be a multitude of causal factors including:

• Instability due to the presence of naturally occurring voids or unmapped mine shafts or workings
• Settlement and compaction of soils due to percolation of water
• Groundwater level fluctuations
• Variation in the moisture content of clay soils

As a result of being based in East Anglia, A F Howland Associates has gained extensive knowledge and experience of subsidence events and their investigations.

Another major cause of subsidence in the East Anglian region is shrinkage/heave movements caused by variations in moisture content of clay soils. Seasonal variation can lead to near surface movement but some species of trees can cause variations in moisture content to much greater depths through the action of their root systems.

Investigation of subsidence events utilises the following methods:

• Exploratory holes (using cable percussive, window sampling or trial pitting methods) to identify features and obtain samples for laboratory analysis
• Dynamic penetration testing to investigate relative soil resistivity
• Foundation inspection pits to determine foundation construction and depth
• Structural and vegetation surveys

Subsequently, recommendations can be formulated to advise upon the most cost efficient solution to the problem.

Litigation & Expert Advice

A F Howland Associates' experience in litigation includes formulating the contractual conditions and specification for term contracts for site investigations such as the London Docklands Development Scheme. We engineered the innovative approach to provide a specific term contract for chemical/environmental investigations as well as one for traditional geotechnical investigations, which is believed to be the first of its kind.

Besides other major industrial activities in litigation, we have also acted for clients in the private sector involved in litigation over:

• Slope stability
• Foundation failures under the influence of adjacent vegetation
• The migration of contamination from adjacent landfill sites
• Dewatering issues and failure of excavation support
• Adequacy of site investigation and the implications on tunnel and shaft construction
• Public enquiries on planning issues and compulsory purchase orders

Contract Research & Development

A F Howland Associates provide a research and development service whereby we are contracted to assess and evaluate construction processes, describe the basic mechanics and develop guidelines for the use of our clients for their respective projects.

We have developed design guidelines for the construction process of soil nailing for use in flood defence systmes for clients sich as the Environment Agency. As part of this service we also described the wider potential of the system, outside of those simply related to embankment stability, as well as exploring the financial options available to the EA for the use of the system.